In one aspect, this invention relates to a process for manufacturing a high-density metal-containing grease. In another aspect, this invention relates to metal-containing greases of a high density which are useful in the down-hole drilling operations of the oil industry, for example. In still another aspect, this invention relates to a method for preparing powdered metals.
The drilling of oil wells continues to be of major importance in todays petroleum industry in light of increased demands for petroleum products. Maintenance of drilling equipment, therefore, is one objective in the effort to keep exploration costs as low as possible. Down-hole turbine drills are one important type of equipment used in petroleum explorations. Proper lubrication of this and other types of drilling equipment is desirable if optimum equipment life is to be achieved.
Adequate lubrication of down-hole turbine drills and similar types of equipment has been a problem because of the environment in which these types of equipment must operate. At the depths and pressures under which these types of equipment operate, dense drilling mud is present. This dense mud envelopes the equipment and, because it is of a higher density than normal lubricants, floats the protecting lubricants away from the equipment. These drilling muds have thus created maintenance problems and rendered normal equipment lubricants inadequate. In order to provide protection to drilling equipment, it has thus become necessary to develop a lubricant which will not be subject to this "floating away" action of the dense drilling mud. One solution is to provide a lubricant which is of a higher density than the drilling muds thereby avoiding the floatation effect of the muds. These muds typically have a density of about 2.5 g/ml with individual particle densities as high as about 4.0 g/ml. Thus, in the case of down-hole drilling operations, lubricants with densities greater than about 2.5 g/ml are desirable.
Conventional high density greases are prepared by mixing metal powders into lubricant bases. These conventional metal powders are formed by comminuting operations such as ball milling, filing, or by reduction from ionic solutions. The shape of metal particles produced by these methods is irregular, and commonly, the particles are flake-like or jagged as opposed to spherical. Thus, preparation of conventional metal containing greases involves either the purchase of such metal powders, or the production of them by one of the above described methods, followed by the mixing of the metal powders into a lubricant base.
It is well known in the art that the addition of finely divided soft metals increases the wear resistance qualities of some lubricants. Previously, the two-step process described above had to be carried out to obtain such metal-containing lubricants. Since the processing of the metal component into powder form is both costly and time consuming, a process which finely divides the metallic component as it is being admixed with the lubricant base is desirable.